Method for forming a weldable mount for fuel systems component

ABSTRACT

A vent apparatus includes a tank mount made of a weldable plastics material and a fuel systems component such as a valve assembly. The valve assembly includes a valve housing made of a non-weldable plastics material and a valve movable in a valve chamber formed in the valve housing to open and close an aperture leading to a venting outlet. The tank mount supports the valve housing in a position in a mounting aperture formed in a fuel tank. The valve housing is made by injecting non-weldable plastics material into a mold containing the pre-molded tank mount.

This application is a continuation of co-pending U.S. application Ser.No. 09/585,085, filed Jun. 1, 2000, now U.S. Pat. No. 6,488,877 whichclaims priority under 35 U.S.C. 119(e) to U.S. Provisional ApplicationSerial No. 60/136,990, filed Jun. 1, 1999, each of which is expresslyincorporated by reference herein.

BACKGROUND AND SUMMARY OF THE INVENTION

The present invention relates a fuel tank valve assembly andparticularly, to a fuel tank valve assembly that is suitable for usewith a fuel tank constructed of a polymeric material. More particularly,the present invention relates to a valve assembly having a mount adaptedto be welded to the fuel tank to mount the valve assembly in a fixedposition in an aperture formed in the fuel tank.

Mounting assemblies are used to mount a venting valve assembly in a topwall of a fuel tank. See, for example, U.S. Pat. No. 4,966,189 to Harrisand PCT International Publication No. WO 99/27284 to Foltz, each ofwhich is incorporated herein by reference. Further, U.S. Pat. No.5,404,907 to Benjey et al. and U.S. Pat. No. 5,130,043 to Hyde bothrelate to weldable vapor vent valve systems and are also incorporated byreference herein.

According to the present invention, a method of forming a vent apparatusadapted to be coupled to a fuel tank is provided. The method includesthe steps of providing a tank mount made of a weldable plastics materialand adapted to be welded to an exterior surface of a fuel tank andinjecting a non-weldable plastics material into a valve housing moldcavity containing the tank mount to overmold the tank mount with thenon-weldable plastics material to produce a valve housing having aventing outlet arranged to communicate with a valve chamber formed inthe valve housing and arranged to extend above the tank mount.

In preferred embodiments, the tank mount is ring-shaped and has eitheran L-shaped, T-shaped, or J-shaped cross section. During the injectingstep, non-weldable plastics material surrounds a portion of thering-shaped tank mount to mechanically couple the non-weldable valvehousing to the weldable tank mount so that a portion of the tank mountcan be welded to the exterior surface of a fuel tank to support thevalve housing in an aperture formed in the fuel tank.

A spring-loaded valve is positioned to move up and down in a valvechamber formed in the valve housing to open and close an aperture formedin a top wall of the valve housing and arranged to provide an openinginto the valve housing venting outlet above the tank mount. The tankmount is positioned to cause a top wall of the tank mount to lie incoplanar relation with the top wall of the valve housing.

Additional features of the present invention will become apparent tothose skilled in the art upon consideration of the following descriptionof preferred embodiments of the invention exemplifying the best mode ofcarrying out the invention as presently perceived.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description particularly refers to the accompanying figuresin which:

FIG. 1 is a perspective view of a weldable ring-shaped tank mount formedto include a circular opening and a valve housing made of a non-weldablematerial and formed to include a circular top wall positioned to lie inthe circular opening formed in the ring-shaped tank mount, a tankventing outlet coupled to and positioned to lie above the top wall, anda cylindrical sleeve coupled to and positioned to lie below the top walland formed to include a valve chamber therein sized to receive a valveas shown in FIG. 2;

FIG. 2 is a sectional view taken along line 2—2 of FIG. 1 showing thering-shaped tank mount welded to a fuel tank made of a weldable plasticsmaterial so that the valve housing is positioned to lie within amounting aperture formed in a top wall of the fuel tank and also showingthe “L-shaped” cross section of the ring-shaped tank mount and aspring-loaded valve positioned to lie and move within the valve chamberin order to open and close the tank venting outlet;

FIG. 3 is a sectional view of a plastic injection mold having an uppermold portion and a lower mold portion, here shown spaced-apart in anopened position, and also showing the ring-shaped tank mountpre-positioned within the upper mold portion prior to injection of anon-weldable plastics material into a mold cavity formed in the upperand lower mold portions (in the manner shown in FIG. 4);

FIG. 4 is a sectional view similar to FIG. 3 showing the upper and lowermold portions in a closed position and a non-weldable plastics materialused to make the valve housing having been injected into a channelformed within the lower mold portion in order to fill both the upper andlower mold portions for the purpose of “over-molding” non-weldableplastics material onto the ring-shaped tank mount to form a valvehousing coupled to the ring-shaped tank mount;

FIG. 5 is a perspective view similar to FIG. 1 showing anotherembodiment of a ring-shaped tank mount made of a weldable material and avalve housing supported by the ring-shaped tank mount and made of anon-weldable plastics material, and also showing a “T-shaped” crosssection of the weldable ring-shaped mount and the manner in which theweldable ring-shaped tank mount is coupled to an annular flange ofcircular top wall of the valve housing;

FIG. 6 is a sectional view taken along line 6—6 of FIG. 5 showing theT-shaped annular tank mount welded to the fuel tank and also showing avalve positioned to lie and move within a valve chamber formed in thevalve housing in order to open and close a tank venting outlet formed inthe valve housing;

FIG. 7 is a sectional view of an alternate plastic injection moldshowing the plastic injection mold having an upper mold portion and alower mold portion, spaced-apart from one another and in an openedposition, and also showing the T-shaped annular tank mountpre-positioned on the lower mold portion;

FIG. 8 is a sectional view similar to FIG. 7 showing the upper and lowermold portions in a closed position to allow the non-weldable plastic tobe injected through a channel into the lower mold portion in order tofill a mold cavity established in the upper and the lower mold portionsin order to “over-mold” the T-shaped weldable tank mount with thenon-weldable plastic, which forms the valve housing;

FIG. 9 is a perspective view similar to FIGS. 1 and 5 showing anotherembodiment of a valve assembly including a ring-shaped tank mount madeof a weldable plastics material and a valve housing supported by thering-shaped tank mount and made of a non-weldable plastics material;

FIG. 10 is a sectional view taken along line 10—10 of FIG. 9 showing asomewhat “J-shaped” cross section of the ring-shaped tank mount that iswelded to the fuel tank and a valve that is positioned to lie and movein a valve chamber formed in the valve housing in order to open andclose a tank venting outlet formed in the valve housing;

FIG. 11 is a is a sectional view of an alternate plastic injection moldshowing the plastic injection mold having an upper mold portion and alower mold portion, spaced-apart from one another and in an openedposition, and also showing the J-shaped annular tank mountpre-positioned on the lower mold portion;

FIG. 12 is a sectional view similar to FIG. 11 showing the upper andlower mold portions in a closed position to allow the non-weldableplastic to be injected through a channel into the lower mold portion inorder to fill a mold cavity established in the upper and the lower moldportions in order to over-mold the J-shaped weldable tank mount with thenon-weldable plastic, which forms the valve housing;

FIG. 13 is a sectional view showing a tank mount mold including anannular tank mount mold cavity having an L-shaped cross section in orderto form the tank mount shown in FIGS. 1 and 2;

FIG. 14 is a sectional view similar to FIG. 13 showing an alternate tankmount mold including an annular tank mount mold cavity having a T-shapedcross section in order to form the alternate tank mount shown in FIGS. 5and 6; and

FIG. 15 is a section view similar to FIGS. 12 and 13 showing anotheralternate tank mount mold including an annular tank mount mold cavityhaving a J-shaped cross section in order to form the alternate tankmount shown in FIGS. 9 and 10.

DETAILED DESCRIPTION OF THE DRAWINGS

A vent apparatus 10 is shown in FIG. 1 and is configured to be mountedon an exterior surface 40 of a fuel tank 18. Vent apparatus 10 is formedto include a weldable tank mount 12 and a fuel systems component coupledto weldable tank mount 12. Tank mount 12 is made from a weldableplastics material and fuel systems component is made from a non-weldableplastics material. In the illustrated embodiment, the fuel systemscomponent is a valve assembly 13 for controlling the discharge of fueland fuel vapor from fuel tank 18. It is within the scope of this.disclosure to use tank mount 12 to support other fuel system components(not shown) such as a fuel sender unit or other type of valve in fueltank 18 or another type of tank.

Valve assembly 13 is formed to include a valve housing 14 and aspring-loaded valve 21. As mentioned above, tank mount 12 of the presentinvention is made from a weldable plastics material such as high densitypolyethylene (HDPE) or any other suitable polymeric plastic or material.Valve housing 14 is molded from a non-weldable plastics material such asacetal, for example. Tank mount 12 is provided for supporting valvehousing 14 in a mounting aperture 16 of fuel tank 18, as shown in FIG.2.

Vent apparatus 10 is provided for mounting within fuel tank 18, as shownin FIG. 2, in order to equalize the pressure between fuel tank 18 andthe atmospheric pressure. Similar to tank mount 12, fuel tank 18 is madefrom a weldable plastics material so that tank mount 12, also made froma weldable plastics material, and fuel tank 18 may be welded together inorder to couple apparatus 10 securely with fuel tank 18. Apparatus 10 ismade using an “over-mold” process in accordance with the disclosureherein wherein tank mount 12 is pre-molded and inserted into a valvehousing mold or plastic injection mold 15, as shown in FIGS. 3 and 4.The non-weldable plastics material, forming valve housing 14, is theninjected around tank mount 12 into a valve housing mold cavity 64 formedin plastic injection mold 15 around tank mount 12. Because of the designof tank mount 12, tank mount 12 becomes mechanically coupled to valvehousing 14 once the non-weldable liquid plastics material injected intomold 15 cools and sets. The process by which apparatus 10 is made willbe described below in more detail.

As stated above, vent apparatus 10 is formed to include tank mount 12and a fuel systems component herein disclosed as valve assembly 13 whichincludes valve housing 14 and valve 21. Valve housing 14 is molded froma non-weldable plastics material. Valve housing 14 is formed to includea circular top wall 20, a venting outlet 22 coupled to and positioned tolie above top wall 20, and a cylindrical sleeve 26 which is coupled toand positioned to lie below top wall 20, as shown in FIGS. 1 and 2.Cylindrical sleeve 26 is hollow and thus defines an interior regionproviding a valve chamber 24, as shown in FIG. 2.

Valve 21 is positioned to lie within valve chamber 24 and operates toopen and close an aperture 23 which is defined by top wall 20 and leadsto venting outlet 22 for purposes of equalizing the pressure within fueltank 18 with that of the atmospheric pressure. Fuel and fuel vapor isconducted from fuel tank 18 to valve chamber 24, through aperture 23,and out venting outlet 22 to another destination, for example, a fuelvapor treatment canister including a carbon filter. Top wall 20 is alsoformed to include an annular flange 27 which defines a channel 28, asshown in FIG. 2, for receiving a portion of tank mount 12 therein.

As mentioned before, tank mount 12 is formed from a weldable plasticsmaterial such as HDPE or any other suitable polymeric plastic. Tankmount 12 is formed to include an interior wall 29 defining a passageway30 for receiving top wall 20 of valve housing 14. Interior wall 29includes an upper portion 44 and a lower portion 46. Tank mount 12 alsoincludes an inner rib 32 coupled to interior wall 29, positioned to liemidway between upper portion 44 and lower portion 46, and positioned toextend into passageway 30. Inner rib 32 is formed to be received withinchannel 28 of flange 27 of top wall 20. Inner rib 32 includes at leastone notch 34 while flange 27 includes at least one corresponding locatortab 31 received within notch 34 in order to prevent rotation betweentank mount 12 and valve housing 14.

Tank mount 12 further includes a body 36 having an “L-shaped” crosssection, as shown, for example, in FIG. 2, adapted to be coupled to fueltank 18. Body 36 includes an annular arm or top wall 37 having a topsurface 47 coupled to interior wall 29 and positioned to extend radiallyoutwardly from interior wall 29 as shown in FIGS. 1 and 2. Body 36further includes an annular foot or outer rim 41 having an outer surface49, coupled to top wall 37 and positioned to extend radially downwardlyfrom top wall 37. Top wall 37 is therefore arranged to extend radiallyinwardly from outer rim 41. Outer rim 41 further includes a downwardlyfacing bottom surface 38 for engagement with exterior surface 40 of fueltank 18. Top surface 47 of top wall 37 has a horizontal length X andouter surface 49 of outer rim 41 has a vertical height Y such that X isgreater than Y as shown in FIG. 2. Valve assembly 13 is positioned tolie within mounting aperture 16 of fuel tank 18 in order to provide amounting arrangement for weldably coupling tank mount 12 of apparatus 10directly to fuel tank 18.

Tank mount 12 is molded using a tank mount mold 66, as shown in FIG. 13.Tank mount mold 66 includes upper and lower mold portions 68, 70 formingan annular tank mount mold cavity 72 having an “L-shaped” cross section.A weldable plastics material is injected into annular tank mount moldcavity 72 by a weldable plastics material injector 74 in order to formring-shaped tank mount 12 also having an L-shaped cross section.

Valve housing 14 is molded using plastic injection mold 15, as shown inFIG. 3. Plastic injection mold 15 includes an upper mold portion 50 anda lower mold portion 52. Upper and lower mold portions 50, 52 aremovable between an opened position, as shown in FIG. 3, and a closedposition, as shown in FIG. 4. Lower mold portion 52 is coupled to aplastics material injector 51 provided for injecting the liquidnon-weldable plastics material such as acetal into lower mold portion 52of plastic injection mold 15.

Upper mold portion 50 is formed to define a mount-receiving cavity 53, atop wall-forming cavity 55, and an outlet-forming cavity 57, as shown inFIG. 3. Lower mold portion 52 is formed to define a sleeve-formingcavity 58. Top wall-forming cavity 55 further includes an inner ribencapsulation portion 76 formed to surround inner rib 32 of tank mount12 when tank mount 12 is positioned to lie in mold 15. As shown in FIG.3, tank mount 12 is pre-molded and inserted within mount-receivingcavity 53 of upper mold portion 50 when upper and lower mold portions50, 52 are in the opened position. Upper and lower mold portions 50, 52are then moved to the closed position, as shown by arrows 54, to retaintank mount 12 within mold 15, as shown in FIG. 4.

Once upper mold portion 50 and lower mold portion 52 are moved to theclosed position, plastic material injector 51 injects the liquidnon-weldable plastics material, such as acetal, through a channel 56formed in lower mold portion 52. The liquid injected plastics materialfills sleeve-forming cavity 58 of lower mold portion 52 first and thenproceeds to fill top wall-forming cavity 55 and nozzle-forming cavity 57of upper mold portion 50. The result is that weldable tank mount 12 isover-molded onto the non-weldable liquid plastics material used to formvalve housing 14.

Once the cavities formed in upper and lower mold portions 50, 52 havebeen filled, the non-weldable liquid plastics material in those cavitiesis allowed to cool. After the liquid plastics material has cooled to asolid form, a mechanical bond is established between tank mount 12 andvalve housing 14 due to the structure of tank mount 12 and valve housing14, as described previously. Once cooled, upper and lower mold portions50, 52 are moved to the opened position and valve housing 14 and tankmount 12, which are now mechanically coupled to one another, are removedfrom mold 15. Venting outlet 22 is positioned to lie above tank mount 12and cylindrical sleeve 26 is positioned to lie below tank mount 12.

Because of the use of the over-molding process disclosed herein, a lowerpercentage of apparatus 10 is able to be made of the permeable weldablematerial which forms tank mount 12. Therefore, the surface area of theweldable plastics material exposed to fuel from fuel tank 18 is reduced.This reduction in surface area may act to reduce the emissions given offin vehicle use. A smaller amount of weldable plastics material is neededto make mount 12 in order to couple valve assembly 13 to fuel tank 18.Further, the non-weldable plastics material used to form valve housing14 may have a tendency to shrink after having been molded. Once valvehousing 14 is injection-molded over tank mount 12, the non-weldablematerial of valve housing 14 will shrink around tank mount 12 in orderto form a tight mechanical bond between tank mount 12 and valve housing14.

Using the method disclosed herein, vent apparatus 10 is formed by firstforming tank mount mold 66 to include annular tank mount mold cavity 72having an L-shaped cross section. The next step is to inject a weldableplastics material into annular tank mount mold cavity 72 in order toprovide ring-shaped tank mount 12. Tank mount 12 also has an L-shapedcross section including annular foot or outer rim 41 having downwardlyfacing bottom surface 38 adapted to be welded to exterior surface 40 offuel tank 18, as shown in FIG. 2. The final step includes injecting thenon-weldable plastics material into valve housing mold cavity 64, whichcontains tank mount 12, in order to over-mold tank mount 12 with thenon-weldable plastics material which forms valve housing 14. Valvehousing 14 is thus formed to encapsulate inner rib 32 in order to form amechanical bond between tank mount 12 and valve housing 14.

Another embodiment is provided in FIGS. 5-8 showing an alternateapparatus 110 including an alternate T-shaped tank mount 112 and analternate valve assembly 113. Valve assembly 113 is formed to include analternate valve housing 114 and valve 21. Tank mount 112 is ring-shapedand configured to form a passageway 130. Tank mount 112 is also formedfrom a weldable plastics material such as HDPE or any other suitablepolymeric plastic.

Alternate tank mount 112, similar to tank mount 12, is molded using analternate tank mount mold 166, as shown in FIG. 14. Alternate tank mountmold 166 includes upper and lower mold portions 168, 170 forming analternate annular tank mount mold cavity 172 having a T-shaped crosssection. The weldable plastics material is injected into annular tankmount mold cavity 172 by a weldable plastics material injector 74 inorder to form alternate tank mount 112 also having a T-shaped crosssection.

Valve housing 114 is molded from a non-weldable plastics material suchas acetal, for example. Valve housing 114 similarly includes a circulartop wall 120, venting outlet 22 coupled to and positioned to lie abovetop wall 120, and cylindrical sleeve 26 defining interior region 24.Cylindrical sleeve 26 is coupled to and positioned to lie below top wall120, as shown in FIGS. 5 and 6. Valve 21 is positioned to lie withinvalve chamber 24 of valve assembly in order to open and close aperture23 of top wall 120 leading to venting outlet 22 for purposes ofequalizing the pressure within fuel tank 18 with that of the pressureoutside fuel tank 18.

Top wall 120 is formed to include an annular flange 127 having aninterior opening forming a T-shaped channel 184, as shown in FIGS. 5 and6. Annular flange 127 includes a top wall 140, opposite side walls 142,144 coupled to top wall 140, and tab portions 146 coupled to side walls142, 144 which collectively define channel 128. Channel 128 is formedfor receiving tank mount 112 therein. As shown in FIGS. 5 and 6, tankmount 112 is also T-shaped and is formed to include a horizontal member160 having a top surface 162 positioned to engage top wall 140 ofannular flange 127 of top wall 120 and a foot or vertical member 164coupled to horizontal member 160 and formed to include a downwardlyfacing bottom surface 138 positioned to engage and weldably couple withfuel tank 18, as shown in FIG. 6.

Valve assembly 113 is positioned to lie within aperture 16 of fuel tank18 in order to provide a mounting arrangement for weldably connectingtank mount 112 of apparatus 110 directly to fuel tank 18 at bottomsurface 138 of tank mount 112. As stated above, fuel tank 18 and mount112 are each made from a weldable plastics material such as HDPE or anyother suitable polymeric plastic. Similar to tank mount 12, alternatetank mount 112 includes notch 34, as shown in FIG. 5. Flange 127includes a locator tab (not shown) formed to be received within notch 34of tank mount 112 in order to prevent rotation between tank mount 112and valve housing 114

Valve housing 114 is molded using a plastic injection mold 115. Plasticinjection mold 115 is similar in structure and function to plasticinjection mold 15, described above, and is shown in FIGS. 7 and 8.Plastic injection mold 115 includes an upper mold portion 150 and alower mold portion 152. Lower mold portion 152 is coupled to the plasticmaterial injector 51 and is formed to define a sleeve-forming cavity158. Upper mold portion 150 is formed to include a top wall-formingcavity 155 and an outlet-forming cavity 157. Tank mount 112 ispre-molded using HDPE or any other suitable weldable plastics material,as described above, and is inserted within plastic injection mold 115,as shown in FIG. 7, when upper and lower mold portions 150, 152 are inthe opened position. Tank mount 112 is shown to be inserted within lowermold 152, however, it is within the scope of this disclosure to insertmount 112 within upper mold 150 prior to injecting the non-weldableplastics material onto mold 115.

Once tank mount 112 is inserted into mold 115, upper and lower moldportions 150, 152 are moved to the closed position, as shown in FIG. 8,in order to retain tank mount 112 therein. When in the closed position,mold 115 forms an annular tank mount encapsulation portion 176 whichcompletely surrounds alternate tank mount 112 except for downwardlyfacing bottom surface 138. Plastics material injector 51 then injectsthe liquid non-weldable plastics material, such as acetal, throughchannel 56 in order to fill sleeve-forming cavity 158, top wall-formingcavity 155, and outlet-forming cavity 157. Tank mount 112 is therebyover-molded with the non-weldable plastics material. Once the liquidnon-weldable plastics material has cooled to a solid form, a mechanicalbond is formed between tank mount 112 and valve housing 114 due to thefact that the non-weldable plastics material has encapsulated alternatetank mount 112 while leaving bottom surface 138 of vertical member 164exposed so that alternate tank mount 112 is able to be welded to fueltank 18. Upper and lower mold portions 150, 152 are then moved to theopened position so that alternate T-shaped tank mount 112 and valvehousing 114 can be removed from mold 115.

Another embodiment is provided and shown in FIGS. 9 and 10. Alternateapparatus 210 includes alternate valve assembly 113, described above,and alternate tank mount 212. As shown in FIGS. 9 and 10, tank mount 212is also ring-shaped and configured to form a passageway 228. Tank mount212 has a somewhat J-shaped cross section as shown, for example, inFIGS. 9 and 10.

Tank mount 212 includes an annular upper T-shaped portion 230 coupled toa foot portion or an annular lower base portion 232. Similar to tankmount 112, upper T-shaped portion 230 of tank mount 212 includes a firsthorizontal member 234 having a top surface 236 positioned to engage topwall 140 of annular flange 127 of top wall 120 and a vertical member 238coupled to horizontal member 234 and lower base portion 232. UpperT-shaped portion 230 is formed to be received within T-shaped channel184 of top wall 120. Therefore, upper T-shaped portion 230 of tank mount212 is mechanically coupled to flange 180 of top wall 120. T-shapedportion 230 may also be formed to include one or more notches 34, asdescribed above and shown in FIG. 9. Annular flange 180 may then beformed to include a locator tab (not shown) to be received within notch34 in order to prevent rotation between tank mount 212 and valve housing114.

Lower base portion 232 of tank mount 12 is generally shaped in the formof a rectangle having a top surface 242, a downwardly facing bottomsurface 244, an interior surface 246, and an exterior surface 248, asshown in FIG. 10. Top surface 242 is positioned to engage one of the tabportions 146 of flange 127 and exterior surface 248 is generally inalignment with side wall 142 of flange 127. Bottom surface 244 of lowerbase portion 232 is adapted to be weldably coupled to fuel tank 18, asshown in FIG. 10. Valve assembly 113 of apparatus 210 is positioned tolie in aperture 16 of fuel tank 18 in order to provide a mountingarrangement for weldably connecting tank mount 212 directly to fuel tank18 at bottom surface 244 of tank mount 212. Similar to the previouslydescribed embodiments, fuel tank 18 and mount 212 are each made from aweldable plastics material such as HDPE or any other suitable polymericplastic. Because tank mount 212 includes lower base portion 232, a userwill be able to see and confirm the weld connection between bottomsurface 244 of lower base portion 232 and fuel tank 18 easily.

Tank mount 212, similar to tank mounts 12 and 112, is molded using analternate tank mount mold 266, as shown in FIG. 15. Alternate tank mountmold 266 includes upper and lower mold portions 268, 270 and oppositeside mold portions 269 forming an alternate annular tank mount moldcavity 272 having a J-shaped cross section. Although mold 266 is shownto include upper, lower, and side mold portions 268, 270, 269,respectively, it is within the scope of this disclosure to provide anymold 266 which forms annular tank mount mold cavity 272. The weldableplastics material is injected into annular tank mount mold cavity 272 bya weldable plastics material injector 74 in order to form alternate tankmount 212 also having a J-shaped cross section.

Vent apparatus 210 is produced using the same injection molding processas described above with reference to vent apparatus 10 and alternatevent apparatus 110. Valve housing 114 of valve assembly 113 is moldedusing a plastic injection mold 215. Plastic injection mold 215 issimilar in structure and function to plastic injection mold 115,described above, and is shown in FIGS. 11 and 12. Plastic injection mold215 includes an upper mold portion 250 and a lower mold portion 252.Lower mold portion 252 is coupled to plastic material injector 51 and isformed to define sleeve-forming cavity 158. Upper mold portion 250 isformed to include top wall-forming cavity 155 and outlet-forming cavity157. Tank mount 212 is pre-molded using HDPE or any other suitableweldable plastics material, as described above, and is inserted withinplastic injection mold 215, as shown in FIG. 11, when upper and lowermold portions 250, 252 are in the opened position. Tank mount 212 isshown to be inserted within lower mold 252, however, it is within thescope of this disclosure to insert mount 212 within upper mold 250 priorto injecting the non-weldable plastics material onto mold 215.

Once tank mount 212 is inserted into mold 215, upper and lower moldportions 250, 252 are moved to the closed position, as shown in FIG. 8,in order to retain tank mount 212 therein. When in the closed position,mold 215 forms an annular tank mount encapsulation portion 276 which isformed to entirely surround upper portion 230 of tank mount 212.Plastics material injector 51 then injects the liquid non-weldableplastics material, such as acetal, through channel 56 in order to fillsleeve-forming cavity 158, top wall-forming cavity 155, andoutlet-forming cavity 157. Tank mount 212 is thereby over-molded withthe non-weldable plastics material in order to mechanically couple valvehousing 114 to tank mount 212.

Once the liquid non-weldable plastics material has cooled to a solidform, a mechanical bond is formed between tank mount 212 and valveassembly 113 due to the fact that the non-weldable plastics material hasencapsulated upper portion 230 of tank mount 212. Lower base portion 232of tank mount 212 is thereby provided to be welded to fuel tank 18.Upper and lower mold portions 250, 252 are then moved to the openedposition so that J-shaped tank mount 212 and valve housing 114 can beremoved from mold 215.

The present invention allows for the attachment of a non-weldableplastics material, such as acetal, to a weldable plastics material, suchas HDPE in order for the finished product to be functional for hot platewelding. Each tank mount 12, 112, and 212, for example, is provided forhot plate welding to fuel tank 18 in order to couple apparatus 10, 110,210 to fuel tank 18.

The over-molding process disclosed herein reduces the amount of weldableplastics material required and thereby reduces the molding difficultieswhich may arise with the use of weldable plastics material. A reductionin the amount of weldable plastics material required would also resultin a cost reduction of that material used. Further, the reduction inweldable plastics material used would facilitate the molding process bydimensionally controlling the non-weldable plastics material portionssuch as valve housings 14, 114. The use of the over-molding processallows a lower percentage of vent apparatus 10, 110, 210 to be able tobe made of the permeable weldable material which forms tank mount 12,112, 212, respectively. Further, the non-weldable plastics material usedto form valve housing 14 may have a tendency to shrink during thecooling process after having been injected into the mold. Therefore, thenon-weldable material of valve housing 14 will shrink around tank mount2 in order to form a tight mechanical bond between tank mount 12 andvalve housing 14 once valve housing 14 is injection-molded over tankmount 12

Although the invention has been described in detail with reference topreferred embodiments, variations and modifications exist within thescope and spirit of the invention as described and defined in thefollowing claims.

What is claimed is:
 1. A method of forming a vent apparatus adapted tobe coupled to a fuel tank, the method comprising the steps of providinga tank mount made of a weldable plastics material and adapted to bewelded to an exterior surface of a fuel tank and injecting anon-weldable plastics material into a valve housing mold cavitycontaining the tank mount to overmold the tank mount with thenon-weldable plastics material to produce a valve housing having aventing outlet arranged to communicate with a valve chamber formed inthe valve housing and arranged to extend above the tank mount.
 2. Themethod of claim 1, wherein the providing step includes the steps offorming a tank mount mold to include an annular tank mount mold cavityhaving an L-shaped cross section and injecting a weldable plasticsmaterial into the annular tank mount mold cavity to produce aring-shaped tank mount having an L-shaped cross section.
 3. The methodof claim 1, wherein the providing step includes the steps of forming atank mount mold to include an annular tank mount mold cavity having aT-shaped cross section and injecting a weldable plastics material intothe annular tank mount mold cavity to produce a ring-shaped tank mounthaving a T-shaped cross section.
 4. The method of claim 1, wherein theproviding step includes the steps of forming a tank mount mold toinclude an annular tank mount mold cavity having a J-shaped crosssection and injecting a weldable plastics material into the annular tankmount mold cavity to produce a ring-shaped tank mount having a J-shapedcross section.